The concept of an active network was put forward in the work by the Defense Advanced Research Projects Agency (DARPA) in 1994 and constitutes the subject of several international conferences, for example International Workshop on Active Networks, IWAN 99 or IWAN 2000.
An active network is a network in which the nodes, or at least some of them, are capable of applying specific processing to some of the messages conveyed by the network. In other words, this means that such nodes must be capable of running an algorithm other the algorithms that have been available to them since their original design.
Within an active network, all nodes are not necessarily provided with this processing ability: one can thus distinguish between active nodes and non-active nodes (i.e. normal nodes).
In the same way, not all messages necessarily require specific processing: one can thus distinguish between active messages (or packets) and non-active (or normal) messages.
In conventional manner, an active message may contain an identifier of an active application. On receiving an active message, an active router can execute the code associated with said active application.
Nevertheless, an active node has limited storage resources, while the number of active applications is, a priori, unlimited.
Thus, one solution in the state of the art consists in providing a server of active applications such that on receiving an active message, an active node contacts the active applications server in order to download the code that corresponds to the active application identified by the active message.
Nevertheless, that state-of-the-art solution is insufficient since it assumes that an active application has only one possible code corresponding thereto. Unfortunately, the Applicant has observed that a given active application can give rise to different codes as a function of specific features of the active node.
For example, the various active nodes in an active network can possess different execution environments. This typically applies when they come from different suppliers and/or when they implement different operating systems (a proprietary operating system specific to a particular supplier, an operating system of the UNIX type, etc.).
Another example is the function of the active node. A conventional case is the distinction drawn between core routers (i.e. routers internal to a given network), and edge routers (i.e. routers at the boundaries of a network).